The present application claims priority to Japanese Application No. P2000-162775 filed May 31, 2000, which application is incorporated herein by reference to the extent permitted by law.
The present invention relates to a liquid crystal display device for use as various display devices and a method of producing the same.
Hitherto, there has been known a system in which a multiplicity of driving substrates (TFT substrates) with pixel transistors mounted thereon for constituting a liquid crystal display device are formed en bloc on a substrate (wafer) and individual TFT substrates are obtained by splitting the substrate along scribed lines.
FIG. 3 is a plan view showing an example of a wiring pattern on such a conventional TFT substrate, and FIG. 4 is a partly sectional view showing an internal laminated structure in the region of line Axe2x80x94A of FIG. 3.
As shown in FIG. 3, the region for forming one TFT substrate 10 is demarcated by scribed lines 2 formed in a grating form on a wafer 1, and each TFT substrate 10 is provided with a display region 12 in which pixel transistors 11 are disposed in a matrix form.
On the outside of the display region 12, there are provided a vertical driving circuit 13 and a horizontal driving circuit 14 for driving each pixel transistor in the display region 12, and, further, on the outside thereof, there are provided a metallic wiring 15 and a plurality of pad portions 16.
The pad portions 16 are arranged in parallel with and along one side of the display region 12 where the horizontal driving circuit 14 is disposed. These pad portions 16 are connected to the metallic wiring 15, and are brought into contact with terminals of an inspection apparatus or the like. Some of the pad portions 16 are provided as dummies which are not connected to the metallic wiring 15.
Common electrode portions 15A are provided at corner portions of the metallic wiring 15, for supplying electric power to each of the driving circuits 13, 14 and the like.
In FIG. 4, a polycrystalline silicon film 22 is provided on an interlayer insulation film 21 provided on a quartz substrate 20, and an Al electrode film 23 and an upper layer light-shielding film 24 are provided thereon. A transparent electrode 26 is provided on the upper side of the upper layer light-shielding film 24, with an interlayer insulation film 25 therebetween.
Interlayer insulation films 27 and 28 are provided at an outer peripheral portion of the polycrystalline silicon film 22, and have an upwardly projected form, thereby forming the groove of the scribed lines.
The upper layer light-shielding film 24 is a conductive light-shielding film formed, for example, of an alloy of Al, Ti or the like. The transparent electrode 26 is constituted of an ITO film or the like, and the interlayer insulation film 25 is constituted of a P-type TEOS film, a SOG (spin on glass) film or the like. The other interlayer insulation films are constituted by appropriately using a silicon oxide film, a silicon nitride film or the like.
In the production of such a TFT substrate, in order to alleviate warpage of the wafer due to stress, each thin film formed on the scribed lines is removed by dry or wet etching and lithography upon each formation of the thin film.
Therefore, the groove of the scribed lines is deepened at the stage of forming the upper-layer light-shielding layer 24, the upper-layer light-shielding layer 24 is left at bottom portions of the scribed lines at the time of processing the upper-layer light-shielding layer 24, and the left portions are exfoliated in cleaning after the processing or the like, leading, for example, to inter-pixel shortcircuit.
In consideration of this problem, as shown in FIG. 4, a structure has been adopted in which the upper-layer light-shielding film is left annularly along the outer peripheral portion of the TFT substrate so that the upper-layer light-shielding film would not easily be exfoliated.
However, where the upper-layer light-shielding film is left annularly along the outer peripheral portion of the TFT substrate, as shown in FIG. 5, the upper-layer light-shielding film 24 (shown by solid line 24A in FIG. 5) is disposed also in the vicinity of the above-mentioned pad portions 16, and the presence of such annular upper-layer light shielding film 24 results in that damage due to static electricity is liable to occur in a liquid crystal step.
As a countermeasure against this problem, the annular upper-layer light-shielding film may be formed at a position away from the pad portions, to thereby prevent the bad influence of static electricity. However, since various registration marks and TEG are disposed on the scribed lines, formation of the annular upper-layer light-shielding film at positions away from the center of the TFT substrate along the entire periphery of the TFT substrate results in that it is necessary to widen the scribed lines for providing a layout space. In addition, chip size is enlarged, and, hence, yield from the TFT substrates is reduced.
In consideration of the above-mentioned situations of the prior art, it is an object of the present invention to provide a liquid crystal display device and a method of producing the same capable of restraining the generation of electrostatic troubles attendant on proximate formation of the annular upper-layer light-shielding film and pads on the TFT substrate without causing an increase in chip size.
In order to attain the above object, according to a first aspect of the present invention, there is provided a liquid crystal display device including one of a plurality of driving substrates formed en bloc on a substrate and produced individually by splitting the substrate along scribed lines, the liquid crystal display device including: a conductive light-shielding film formed annularly along a peripheral portion of the driving substrate, and a plurality of pad portions arranged on the inside of the conductive light-shielding film along one side of the driving substrate, wherein the spacing between the conductive light-shielding film and each pad at the side of the driving substrate where the pad portions are provided is at least 10 xcexcm.
According to a second aspect of the present invention, there is provided a method of producing a liquid crystal display device including one of a plurality of driving substrates formed en bloc on a substrate and produced individually by splitting the substrate along scribed lines, the method including: a step of forming a conductive light-shielding film annularly along a peripheral portion of the driving substrate, and a step of forming a plurality of pad portions arranged on the inside of the conductive light-shielding film along one side of the driving substrate, wherein the spacing between the conductive light-shielding film and each pad at the side of the driving substrate where the pad portions are provided is at least 10 xcexcm.
In the liquid crystal display device according to the present invention, the spacing between the conductive light-shielding film and each pad at the side of the driving substrate where the pad portions are provided is at least 10 xcexcm.
The spacing of at least 10 xcexcm has been found to be a value capable of reducing the rate of troubles occurring due to static electricity. Therefore, by setting the spacing between the conductive light-shielding film and each pad to be at least 10 xcexcm, troubles due to static electricity between the conductive light-shielding film and each pad can be restrained.
In addition, since the spacing of at least 10 xcexcm between the conductive light-shielding film and each pad is provided only at the side of the driving substrate where the pad portions are disposed, the conductive light-shielding film is not spaced away from the center along the entire periphery of the driving substrate, and the desired layout can be realized without much enlarging the chip size.
Also, in the method of producing a liquid crystal display device according to the present invention, the spacing between the conductive light-shielding film and each pad at the side of the driving substrate where the pad portions are provided is set to be at least 10 xcexcm.
Therefore, by setting the spacing between the conductive light-shielding film and each pad to be at least 10 xcexcm, troubles due to static electricity between the conductive light-shielding film and each pad can be restrained.
Besides, the spacing of at least 10 xcexcm between the conductive light-shielding film and each pad is provided only at the side of the driving substrate where the pad portions are provided, the conductive light-shielding film is not spaced away from the center along the entire periphery of the driving substrate, and the desired layout can be realized without much increasing the chip size.
The above and other objects, features and advantages of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings which show by way of example some preferred embodiments of the invention.